More recently lawn mowers with catchers which are provided with cutting blades mounted for rotation about a generally vertical axis have been modified to mulch as well as catch grass. They perform poorly when used as a mulcher particularly when using a blade disc and swing back blades, that are the same as those used for good grasscatching.
One problem confronted by the use of grasscatching blades is properly dispersing the clippings. Until now the clippings have tended to clump and remain on the surface.
A further problem that results from the above short comings is that the cuttings detract from the appearance of a cut lawn and secondly the cuttings tend to find their way into the home.
The above problems are exacerbated if the grass is damp or wet.
Further, the traditional blade bar used for mulching does not cut the grass cleanly once the cutting edge has become worn, frequently the grass will look bruised, ragged and not uniform.
A further disadvantage of mulching bars is that they can cause damage to the engine crankshaft.
The use of mulching bars has also required a greater power output from the lawn mower motor.
U.S. Pat. Nos. 5,094,064, 3,085,386 and 3,220,170 describe and depict examples of the above discussed mulching bars.
U.S. Pat. No. 5,561,972 describes a mulching disc. The device of this particular USA patent also fails to perform satisfactorily as the air circulation generated fails to convey the cuttings efficiently.